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# Viewing our Solar System from 100 light years away

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### #1 Philip Levine

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Posted 27 July 2013 - 05:02 PM

I have a project to solve: viewing our Solar System from 100 light years away, I would like to calculate the arc second separation between the Sun and Jupiter. The view toward our Solar System from 100 light years out, optimally would be chosen to be perpendicular to the ecliptic - so that the orbit of Jupiter around the Sun would have the most symmetrical orbit.
Is there a software program to visualize such a scenario, and to calculate the arc second separation between Sun and Jupiter?
thanks,
Phil

### #2 Octans

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Posted 27 July 2013 - 06:45 PM

You could probably visualize it with Celestia: http://www.shatters.net/celestia/

The separation can be calculated pretty easily with math.

Wikipedia says Jupiter is 778,547,200 km from the Sun. That converts to 8.22942617 × 10^-5 light years. Then, use that and 100 ly as the legs of a right triangle and use the arctangent function to find the measure of the angle attached to the 100 ly leg.

```      /|
/   | 8.22942617 × 10^-5 ly
/)_____|
100 ly
```

In the crude illustration above, you're measuring the angle on the left, so just arctan(8.22942617 × 10^-5 / 100).

It comes out to be 4.715113873554 × 10^-5 degrees, or about 0.17 arcseconds.

### #3 beatlejuice

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Posted 27 July 2013 - 08:08 PM

Bad weather where I am also. I did the same calculation using light-hours(Jupiter is .75 light-hours from the sun) and came up with the same .17 arc seconds.
As far as viewing this on a computer screen it would be a dot(the sun) and nothing else unless you used a zoom feature which defeats the purpose of observing from 100 light years away.

Eric

### #4 Octans

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Posted 28 July 2013 - 05:23 PM

Well, thanks to perspective flattening, the Sun and Jupiter would be to scale as would the distance between them. I presume the view would look something like:

```O               <very, very wide gap>                   .
```

where the Sun is the O and . is Jupiter.

Of course, for an accurate simulation, the Sun would be many, many, many times brighter and you'd probably be blinded by the brightness of the Sun if the display was bright enough for Jupiter to be visible.

### #5 Philip Levine

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Posted 28 July 2013 - 07:31 PM

Thanks for replies.
I was curious if Jupiter had developed into a star, how this binary star system might stack up against other binary systems.
So it seems looking at our Solar System from 100 light years away, perpendicular to the ecliptic, Jupiter with it's elliptical orbit would average ~.17 arcsecond separation from the Sun, at at perihelion would be about .16 arcsecond from the Sun, and about .18 arcsecond at aphelion.
Jupiter, at ~5.2 AU distance from the Sun, perhaps is too close to the Sun, to have made a stable binary system. Just speculation on my part, I am just getting into the subject of binary stars.

thanks for the explanation on the calculations,
Phil

### #6 Octans

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Posted 28 July 2013 - 10:06 PM

I think such a system should be quite stable. AM CVn stars have orbital periods on the order of an hour (ie. MUCH, MUCH closer together than the Sun & Mercury whose orbital period is 88 days): http://en.wikipedia....iki/AM_CVn_star Jupiter orbits the Sun once every 12 years so any binary system with a shorter period (ie. a LOT of them) have components that are closer by Kepler's third law.

### #7 mikarl_b

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Posted 02 August 2013 - 03:45 PM

Jupiter turning into a star wouldnt change the orbit into a unstable one, why would it?

Mikael

### #8 Roger Corbett

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Posted 03 August 2013 - 11:17 AM

Phil, great idea! It would be intriguing to arrange a series of double stars, their masses, and separations vs. planetary masses and separations. And to visualize that from afar in an astro program (or app) is a good notion.

One can also imagine this as doing the Kepler telescope biz in reverse... imagine a civilization 100 light years away with its Kepler (functioning) in the sky and imaging a G5-star (Sun) to see if it had planets.

It'd be great fun to see what that would look like--in the data, in the light curve, in a Hubble+ larger planet-discovery purposed scope, etc.

### #9 Philip Levine

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Posted 03 August 2013 - 04:42 PM

Hi Mikael,
I was speculating if Jupiter was a star, being ~ 5.2 AU from the primary star, that two suns would make for a less stable system - at least for planets in such a system.
Maybe Earth would have developed in the same manner as it has with one sun, perhaps not.
The exercise to calculate the arc second separation between the Sun and Jupiter, from an arbitrary distance of 100 light years, was so I could compare the separation to other binary star systems. I'm still searching the web to see statistically, how our imaginary binary system (Sun and Jupiter) would compare to other binary systems - by selectively looking at arc second separation.
If anyone knows of a good web resource for binary stars, please let me know.
Just speculation on my part, I'm not an astrophysicist.
If two suns would have precluded Earth from developing into a stable planetary environment, we should thank our lucky stars we just have one.
Phil

### #10 Octans

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Posted 04 August 2013 - 02:13 AM

If Jupiter were to be replaced by a copy of the Sun today, I think the Earth would probably be ejected from the solar system pretty rapidly (ie. maybe in just a year or so). At the closest point, Earth is 4 AU from Jupiter and 1 AU from the Sun which would make the gravitational attraction from the modified Jupiter 1/16 the strength of the Sun -- significant enough to seriously disrupt Earth's orbit. On the other hand, if this second sun were to be say >100 AU away, I don't think it would make much of a difference to what happened in the early inner solar system, although of course, with the butterfly effect of changing events in history, Earth might still not have formed, but there wouldn't be anything precluding its formation.

Wikipedia has plenty of info on binary systems. What particular type of information are you looking for?

### #11 Philip Levine

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Posted 04 August 2013 - 11:20 AM

Hi Octans,
I want to thank you for simplifying the task to calculate the arc second separation between the Sun and Jupiter, from 100 light years out.
The binary star data I am looking for would be a listing of binary star systems, including distances from our Solar System. For comparison purposes (comparing to Sun and "star" Jupiter from 100 ly out), I would start looking at binary systems ~ 100 light years from our Solar System. Then expand by looking at binary systems 200, 300 lights years out etc. In such binary systems, it might be instructive to see if a number of exoplanets have been found within these binary star systems.
Since binary star systems seem to be very common, I thought it might be interesting to note the statistical spread on how many of these systems have multi-exoplanets within the system. But maybe there is not yet enough data on exoplanet discovery to make a meaningful project.
Just one exercise to speculate on determining the possibility of life outside our Solar System - if binary stars preclude the possibility of a stable planetary system, then perhaps the Drake equation can be further refined. Which would indicate life outside our Solar System has a lower probability, if binary star systems “discourage” life from developing.
This started out with a question for a software program to calculate binary star separation, but the thread might be more appropriate to another CN forum. Not really a "Double Star" observing question, perhaps more a "Astronomy: Space and Exploration" topic.
Again, thanks,
Phil

### #12 Octans

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Posted 07 August 2013 - 03:38 PM

I used VizieR to retrieve a list of catalogs of multiple stars: http://vizier.u-stra.../viz-bin/VizieR (on the right, select "Binaries:Spectroscopic" and select "Find Objects" and here are 436 of them you can start with: http://vizier.u-stra...-3?-source=V/60 (make sure to change the output format & number on the left before you submit). Once you've found an object of interest, you can then go to Simbad and type it in for more info on that object: http://simbad.u-strasbg.fr/simbad/ For exoplanets, you can enter the star name here to check: http://planetquest.j.../newworldsatlas

### #13 Philip Levine

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Posted 19 August 2013 - 07:15 AM

Hi Octans,
Certainly some in-depth resources on the links you provided.
Enough to keep me busy and then some.
Thanks very much for your excellent replies.
Phil

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